noun
primeval forest; virgin forest
Refers to a forest that has remained largely untouched by human activity, preserving its original ecosystem.
この地域には広大な原生林が残っている。
A vast primeval forest remains in this region.
自然林 is a broader term for natural forests, including secondary forests that have regrown naturally, while 原生林 specifically denotes untouched, ancient forests.
Compound of 原生 (primeval, original) and 林 (forest).